The preferred embodiment relates to a method and an arrangement for generating authentication information by means of which a data processing system performs an authentication of a control unit. The preferred embodiment further relates to a method and an arrangement for authenticating a control unit of an electrophotographic printing or copying system.
Known electrophotographic printers and copiers have communication interfaces over which the control units and maintenance computers can be linked with the printer or copier for purposes of control, diagnostic analysis, and maintenance. In particular, security related settings of the printer or copier can be changed with the aid of the maintenance computers. If such modifications are performed by insufficiently qualified operators or unauthorized persons, e.g. over a network connection, the result may be a significant quality degradation and damage or destruction of assemblies of the printer or copier.
In the case of known printers and copiers, a number of so-called user levels are provided, whereby a user can select a user level and verifies his authorization to select this user level by inputting a password. Furthermore, with known printers and copiers, unauthorized persons may be able to acquire information about the structure and control structure of the printer or copier through unsecured access with the aid of the communication interface of the printer or copier. System parameters such as meter counts of the printer or copier, which may be used for billing purposes, can also be manipulated over the communication interface of known printers or copiers.
The European Patent EP 0 513 549 A2 describes an arrangement for controlling and transmitting data between a host computer and a copier control, whereby the communication does not occur until the successful identification of the host computer with the aid of a password. A control unit for communication control is also provided.
U.S. Pat. No. 5,077,795 describes an electronic printing system in which the security of user data and user programs is ensured with the aid of a user profile for each user. The user profiles are managed by a security administrator on site or at a remote location.
However, known access methods offer only an inadequate protection of the printer's internal data and settings. In particular, a substantial risk associated with passwords is that they can be spied on with the aid of program modules that record the keyboard inputs. Another security risk associated with passwords is that they must be delivered to the respective user, whereby it often cannot be guaranteed that unauthorized parties will not acquire knowledge of the passwords during the transmission and/or delivery of the passwords. Nor is there any guarantee that authorized parties will not disseminate the passwords to unauthorized parties. An effective local protection of known printers or copiers could only be achieved by preventing unauthorized parties from gaining physical access to the communication interface of the printer or copier. But in that case the print data could not be transmitted to the printer over a network that is also linked to global networks such as the Internet over which unauthorized parties also have access to the printer. But such techniques also foreclose the possibility of remote maintenance, remote diagnostic analysis, or remote control of the printer by service specialists that are not on site.